1. Field of the Invention
The present invention relates to a compact zoom lens having a high zoom ratio and suitable for image pickup apparatuses such as digital still cameras and video cameras.
2. Description of the Related Art
Image capturing optical systems used for image pickup apparatuses (cameras) are required to be compact as a whole, capable of reducing a thickness of the camera and configured as a zoom lens having a high zoom ratio.
There is known a retractable zoom lens which reduces distances among mutually adjacent lens units in a non-image capturing state to different distances from those thereamong in an image capturing state, whereby the lens units are retracted inside a camera body. There is also known a so-called bent zoom lens in which a reflective mirror that bends an optical axis of the image capturing optical system by 90 degrees is disposed in its optical path. There is further known a bent zoom lens that bends its optical path by using the reflective mirror in the image capturing state and that rotates the reflective mirror in the non-image capturing state to retract an object-side lens unit in a space formed by the rotation of the reflective mirror.
Japanese Patent Application Laid-open No. 2007-279541 discloses a bent zoom lens in which a reflective mirror is disposed between a second lens unit and a third lens unit counted from an object side and which rotates the reflective mirror in the non-image capturing state to retract a front unit on the object side further than the reflective mirror in a space formed by the rotation of the reflective mirror.
U.S. Pat. No. 7,630,142 discloses a zoom lens in which a reflective mirror between a third lens unit and a fourth lens unit counted from an object side and which rotates the reflective mirror in the non-image capturing state to retract a front unit on the object side further than the reflective mirror in a space formed by the rotation of the reflective mirror.
Furthermore, there is known a bent-retractable zoom lens which moves in the non-image capturing state a reflective mirror to a space different from that in the image capturing state, whereby a lens unit on an object side further than the reflective mirror is retracted.
U.S. Pat. No. 7,692,869 discloses a zoom lens in which a reflective mirror is disposed between a second lens unit and a third lens unit counted from an object side and which moves the reflective mirror and a lens unit disposed on an image side further than the reflective mirror to retract an object-side lens unit in a space formed by the movement thereof.
Such zoom lenses provided with the reflective mirror which bends the optical path of the image capturing optical system are likely to simultaneously realize a high zoom ratio and thinning of a camera. However, in order to achieve these advantages, it is important to appropriately set a lens configuration of the zoom lens, arrangement of the reflective mirror in the optical path, configurations of the respective lens units on the object and image sides further than the reflective mirror and others.